It has been 49 years since Michael Caine last set foot in Cannes. “I was here with a film called Alfie,” said the actor, now 82. “It won a prize and I didn’t. So I never came back. I’m not going all that way for nothing.”

But Caine has broken his rule book for his new film, Youth, the second English-language movie by Italian director Paolo Sorrentino, who won an Oscar two years ago for The Great Beauty.

“I love this film,” said Caine. “I’d have done it one for free, but I didn’t tell the producers.”

Youth is winning rave reviews for Caine, who plays an celebrated conductor holed up in a Swiss spa hotel with his daughter (played by Rachel Weisz) and a film director friend (Harvey Keitel), having flashbacks to his past, dismissing offers of work – and reading the Guardian.

Youth is a meditation on the ageing process – Caine’s character feels he’s losing his memory, and there are many scenes of his liver-spotted skin wrinkling beneath the touch of the hotel’s massage staff.

Caine said he was happy to be taking on such roles. “The only alternative to playing elderly people is playing dead people. So I picked elderly people. That’s a better idea.” He realised he was entering a new stage in his career, he said, when he was sent a script to read but rejected it feeling the part was too small.

Caine and the director, Paolo Sorrentino, at the press conference. Photograph: Thibault Camus/AP

“The producer said: ‘I didn’t want you to read the lover, I wanted you to read the father.’ I then realised that I wouldn’t get the girl anymore, but I would get the parts. I got a couple of Academy Awards after that so it was ok.”

He hoped the shots of his body, clad only in a small towel, would serve as a caution. “It’s the only body I’ve got. At least it was a reality. Young people should know: this is what’s going to happen, do don’t get too smart about it.”

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For Caine, the title made him think of a scene - depicted on the film’s poster - in which his and Keitel’s characters are joined for a dip by the current Miss Universe. “Us two old guys in swimming pool looking at beautiful girl with no clothes. That is youth. We’re looking at what we’ve lost and never going to get again. It’s a very sad poster. It makes me cry.”

Caine was joined by his director, who was last at the festival in 2013 with The Great Beauty. Sorrentino said he hoped his new film was an “optimistic” one which “dispels our fears” about the “only subject of interest to anyone: how much time we have left”.

Jane Fonda, who plays a veteran star courted by Keitel, concurred. “This movie says something I agree with, that age is a question of attitude. You remain vital in your mind when you have passion. I do and the film does.”

Caine said he too struggled with memory loss as he gets older, having forgotten a joke the Queen once told him at a party. His character in the film is implored by an emissary for the monarch to conduct his most famous work at a concert for Prince Phillip’s birthday. He refuses, and voices the opinion the Queen is never that enthusiastic about anything. In the flesh, said Caine said, she’d always been perfectly friendly.

Caine and Keitel at a photocall for the film. Photograph: IAN LANGSDON/EPA

“She doesn’t say much but when she knighted me she said: ‘I have a feeling you have been doing what you have been doing for a very long time.’ I almost said: ‘And so have you.’ But then I thought: ‘Keep your mouth shut, Michael, you’re about to lose your knighthood, you’ll get beheaded.”

Caine paid tribute to his fellow cast members, including the actor Paul Dano (who plays a cynical Hollywood star also holidaying at the resort) likening ensemble work to warfare. “I was a soldier once and it’s a bit like that. You’re going to go into this exremely dangerous situation where unless you look out for yourselves and each other you get wounded or killed.”

Dano’s character is struggling with typecasting which has come as a result of playing a robot in an action franchise. Fonda said she felt similar ambivalence about being best known for Barbarella, the cult 1968 science-fiction film in which she plays a minimally-clad futuristic sex warrior.

“It stuck to me and I am conflicted,” said Fonda. “That’s all I have to say on the subject.”

Caine said he didn’t feel defined by Alfie, which was “a long time ago in every way. It’s about this womaniser going around screwing everybody. I’ve been married for 46 years to the same woman. If I had to play Alfie again he wouldn’t be so virile.”

Weisz said she was proud of her work on The Mummy franchise, and of being often recognised by children because of it, while Dano said his role as a geeky best friend in 2004 romcom The Girl Next Door had felt very “defining”. “But at the end of the movie it’s revealed my character has a very large penis, so that’s been nice.”